Having trouble with If Then command:

[dbeck114]

Hello to all, I have completed a class assignment and wanted to expand using an If Then module to determine if an input is either a number or a specific letter. I've been searching forums and have found several examples that I have tried to make work but am unable to succeed as of yet. The VB project is in console mode and I will attempt to cut and paste the code so you can take a look at it. Now, here's a discription of what my program is supposed to do. My program asks for numerical values to input to calculate the area of a triangle. I want to add an if then statement in the event that the input is not a number it will re-ask the user to input the number again. Here is what I have so far.

Sub Main()
Dim Number As Integer
Dim Display As String
Console.WriteLine("Please input a number")
Dim input = Console.ReadLine()


If input(Number) = True Then
Number = Val(Number)
If Number < 1 Or Number > 100 Then
If Number > 100 Then
Console.WriteLine(" The Number You entered is too high")
ElseIf Number < 1 Then
Console.WriteLine(" The Number You entered is too low")
ElseIf Number >= 1 And Number <= 100 Then
Process1.Enabled = False
End If
Else
Display = " The number you entered is not between 1 and 100"
End If
Else
Display = " You did not enter a numerical value "
End If


End Sub

How can I cut and paste what I have on VB to be the same in this forum. I used WYSIWYG and it still does not look like what I have on VB.

Thanks

[techgnome]

put [CODE][/CODE] or [HIGHLIGHT=VB][/HIGHLIGHT] tags around the code...

for starters though.... these two lines shouldn't work....

If input(Number) = True Then
    Number = Val(Number)

The first should produce a compile error...

Input is going to be a string because that's what Console.ReadLine() returns.
Number is an integer, but hasn't been assigned a value yet so it's not really valid...
Then you have Number = Val(Number) ... but Number is still empty, and even if it did, it would already be an integer (because that's what Number has been defined as) ... making Number = Val(Number) redundant.

I'm guessing that's not really what you wanted....

Try this instead:

If Integer.TryParse(Input, Number) Then
    If Number < 1 Or Number > 100 Then 
        If Number > 100 Then

This condition will never run:

ElseIf Number >= 1 And Number <= 100 Then

It is found inside the first check for out of bounds...



here's a little quick restructuing:

If Integer.TryParse(Input, Number) Then
    If Number < 1 then
        console.writeline("Value too small")
        Display = "Value entered is not between 1 and 100"
   elseif Number > 100 then
        console.writeline("Value too large")
        Display = "Value entered is not between 1 and 100"
    else ' No need for any further checking we know it's between 1 and 100
        Process1.Enabled = False
    End If
Else
    Display = " You did not enter a numerical value "
End If

-tg

[dbeck114]

I will give it a try, Thank You...so many questions, so little time in the day!

[dbeck114]

Ok I've been working on this now for several hours and am still having some issues. Maybe I just need to simplify this by breaking it down into two steps. Here is what I now have.

Module Module1
 
    Sub Main()
        Console.WriteLine("please enter a number between 1 and 9, or one of the following letters a, b or c")
        'here is where I would like the program to determine if the input is a number or a letter
        'unfortunatly my text book in on program structure and not on VB so no useable code is 
        'in the book.  
        Dim input = Console.ReadLine()
        If input <= 1 OrElse >= 9 Then
        Else input <> (a,b,c) then
            Console.WriteLine("Im sorry, but you did not enter one of the designated characters.  Please try again")
 
 
        End If
 
 
    End Sub
 
    
End Module

[Peter Swinkels]

Does this do what you want?

Option Compare Binary
Option Explicit On
Option Infer Off
Option Strict On

Imports System

Public Module AreaModule
   Public Sub Main ()
      Dim Area As Integer = 0
      Dim Side1 As Integer = 0
      Dim Side2 As Integer = 0

      Side1 = GetNumber("Length of side #1: ")
      Side2 = GetNumber("Length of side #2: ")
      Area = CInt((Side1 * Side2) / 2)

      Console.Write ("The triangle's area: ")
      Console.Write (CStr(Area))
   End Sub

   Private Function GetNumber(Prompt As String) As Integer
      Dim UserInput As String = Nothing

      Do
         Console.Write (Prompt)
         UserInput = Console.ReadLine().Trim
      Loop Until Integer.TryParse(UserInput, New Int32)

      Return CInt(CInt(UserInput))
   End Function
End Module

The program checks whether the user's input is a valid number using the TryParse() function.

Hope this helps.